Sources tell The Weekly Online that Michelle, 44, is 18 weeks pregnant and due to give birth just after Christmas. The child will be Commando’s fourth. The 39-year-old former special forces soldier already has three children from two previous relationships.

Michelle was among a slew of guests at fellow fitness doyenne Lorna Jane’s book launch in Sydney last week, looking radiant. Friends of Commando say he is “over the moon”.

The couple met on the set of the television show Biggest Loser, which is returning to screens on Network Ten later this year.

Michelle Bridges confirmed the happy news on Twitter.

"We're so happy to announce our special news," she wrote.

"The well wishes and love received already are overwhelming & beautiful. Michelle + Steve."

In May 2013, Michelle split from her husband of nine years and business partner, Bill Moore, to be with Commando. Commando left his partner, Froso, to start a relationship with Michelle. He has two children with Froso – Ella, 6 and Jack, 3. He also has an older daughter, Brianna, from a previous relationship.

In an interview with The Australian Women’s Weekly in 2012, Michelle – then 41 - said she was reconciled to the idea that she may not have children.

She and Commando have been fixtures of Sydney’s Potts Point café scene, where they live. Yesterday the pair appeared on the streets – but not even Michelle’s large puffer coat could disguise a tiny bump.